“…In several study designs, the siblings recruited were concordant on traits such as sex (Bosk, 1988;Roemmich et al, 2010;Tripicchio et al, 2014;Ufholz et al, 2020) and age (twins or retrospective data collection for one sibling) (Damen et al, 2020;Harris et al, 2016;Selzam et al, 2018;Tripicchio et al, 2014). In other designs, researchers intentionally recruited siblings discordant on traits such as weight status (Bosk, 1988;Roemmich et al, 2010;Saelens, Ernst, & Epstein, 2000;Ufholz et al, 2020) or during analysis, identified subsamples of siblings discordant on traits such as sex (Berge, Meyer, et al, 2016), weight status (Berge, Meyer, et al, 2016;Berge, Tate, et al, 2016;Moens, Braet, & Vandewalle, 2013), and eating behaviours (Harris et al, 2016). Few studies reported on methodologies (n = 1) and theoretical frameworks (n = 4) used.…”